Preserving in fat, step by step
Interactive lesson: what fat, oil, honey and sugar really preserve, four barriers against spoilage, choosing fat and containers, the fat seal, the cold larder and rancidity.
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The whole lesson as text
1. Who does what
Fat, oil, honey and sugar all cover food, but only two of them really preserve it.
- Fat seals — Pork lard, tallow and goose fat seal food off from air and light. They don't kill germs and don't prevent botulism.
- Oil the same — Oil works like fat, only liquid. It doesn't preserve vegetables or cheese, and fresh garlic in oil is a classic cause of botulism.
- Honey binds water — Honey binds water and is mildly acidic, so good honey doesn't ferment for years. But only honey with no more than 18 % water.
- Enough sugar — Slatko (whole fruit in thick syrup) and jam are kept by 60–65 % sugar. In a thin syrup sugar doesn't protect; there only the water bath does.
Why: Germs and moulds live in water. Pure fat and oil contain no water, but the meat, cheese and vegetables lying in them contain plenty. Honey and sugar bind water to themselves and leave too little for germs.
- Fat and oil are a lid; the real work is done by salt, heat, cold, acid or enough sugar.
- Botulinum toxin can't be seen, doesn't smell and doesn't change the taste. Safety is checked with the method, not with your nose.
2. Four barriers
No barrier needs to be enough on its own, but together they stop spoilage.
- Salt — Salt binds the water in meat and slows germs. For meat in lard, roughly 2–2.5 % of the meat weight.
- Heat — Cooking kills most germs. The meat must be fully cooked, hot in the middle, with no red juices.
- Cold — Below 10 °C (50 °F) germs rest, and below 4 °C (39 °F) they almost stop. For meat in lard this barrier is essential.
- Acid or sugar — pH below 4.6 or 60 % sugar. That is how vegetables in oil to a tested recipe, walnuts in honey and slatko keep.
Why: A product for the larder must have at least two reliable barriers, and food in fat and oil usually three. Roast meat in lard is kept safe by salt, heat and cold; the lard only seals it.
- Cold is the barrier most easily lost: a cellar that was 5 °C (41 °F) in January is 14 °C (57 °F) in May.
- Every recipe in the series tells you which barrier keeps the food safe and where the product may be stored.
3. Fat and containers · Locked
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4. From raw material to container · Locked
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5. Larder and taking out · Locked
Buy the Preserving in fat module and you get the PDF to download and print, plus lifetime access to this interactive lesson: all 6 chapters, 26 steps.
6. Rancidity and stocks · Locked
Buy the Preserving in fat module and you get the PDF to download and print, plus lifetime access to this interactive lesson: all 6 chapters, 26 steps.